Create realtime client

Author: zachaysan

lib/flagsmith/sdk/realtime_client.rb

@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'logger'
+require 'faraday'
+require 'json'
+
+module Flagsmith
+  # Ruby client for realtime access to flagsmith.com
+  class RealtimeClient
+    attr_accessor :running
+
+    def initialize(config)
+      @config = config
+      @thread = nil
+      @running = false
+      @main = nil
+    end
+
+    def endpoint
+      "#{@config.realtime_api_url}sse/environments/#{@main.environment.api_key}/stream"
+    end
+
+    def listen(main, remaining_attempts: Float::INFINITY, retry_interval: 0.5) # rubocop:disable Metrics/CyclomaticComplexity, Metrics/AbcSize, Metrics/MethodLength
+      last_updated_at = 0
+      @main = main
+      @running = true
+      @thread = Thread.new do
+        while @running && remaining_attempts.positive?
+          remaining_attempts -= 1
+          @config.logger.warn 'Beginning to pull down realtime endpoint'
+          begin
+            sleep retry_interval
+            # Open connection to SSE endpoint
+            Faraday.new(url: endpoint).get do |req|
+              req.options.timeout = nil # Keep connection alive indefinitely
+              req.options.open_timeout = 10
+            end.body.each_line do |line| # rubocop:disable Style/MultilineBlockChain
+              # SSE protocol: Skip non-event lines
+              next if line.strip.empty? || line.start_with?(':')
+
+              # Parse SSE fields
+              next unless line.start_with?('data: ')
+
+              data = JSON.parse(line[6..].strip)
+              updated_at = data['updated_at']
+              next unless updated_at > last_updated_at
+
+              @config.logger.info "Realtime updating environment from #{last_updated_at} to #{updated_at}"
+              @main.update_environment
+              last_updated_at = updated_at
+            end
+          rescue Faraday::ConnectionFailed, Faraday::TimeoutError => e
+            @config.logger.warn "Connection failed: #{e.message}. Retrying in #{retry_interval} seconds..."
+          rescue StandardError => e
+            @config.logger.error "Error: #{e.message}. Retrying in #{retry_interval} seconds..."
+          end
+        end
+      end
+
+      @running = false
+    end
+  end
+end